How is a fly different from a mosquito?

There are 20 people in an empty, square room. Each person has full sight of the entire room and everyone in it without turning his head or body, or moving in any way (other than the eyes). Where can you place an apple so that all but one person can see it?

What begins with T, ends with T, and has T in it?

If we change the South-East direction into North and North-East into West and all others similarly.
Can you find out which direction will be in the place of South-West direction?

Use only one mathematical symbol and all numbers (0-9) to get a sum of 99

Why do you find that most of the buildings are deprived of the 13th floor?

Can you replace the question mark with the correct number in the below table sequence?

Some friends went on a vacation to a resort. It was raining heavily and it kept raining for thirteen days.

When it rained in the morning, the afternoon was beautiful and when it rained in the afternoon, the day was blessed with a clear morning.

Overall, the friends experienced eleven nice mornings and twelve nice afternoons. Can you find out the number of days they spent on vacation?

A network of 20 x 10 squares is given to you.

Can you calculate how many unique squares and rectangles can be formed combining two or more individual squares ?

Three doctors said that Bill was their brother. Bill says he has no brothers. How many brothers does Bill actually have?